Heat Treatment of Metals ›› 2022, Vol. 47 ›› Issue (1): 125-129.DOI: 10.13251/j.issn.0254-6051.2022.01.021

• MATERIALS RESEARCH • Previous Articles     Next Articles

Effect of Ti micro-alloying on microstructure and properties of 22MnB5 hot press forming steel

Zhu Henan, Chen Gang, Yang Jiawei, Zhang Zhijian   

  1. Institute of Research of Iron and Steel, Shasteel, Suzhou Jiangsu 215600, China
  • Received:2021-06-01 Revised:2021-08-26 Online:2022-01-25 Published:2022-02-18

Abstract: Through thermal expansion test, microstructure analysis and hardness test, the effect of cooling rate and Ti element on the phase transformation temperature, microstructure, precipitated phase and hardness of two 22MnB5 hot forming steels was analyzed, and then the CCT curves was obtained. The results show that the microstructure of the tested steels are composed of ferrite and pearlite when the cooling rate is lower than 5 ℃/s; bainites appear when the cooling rate reaches 5 ℃/s, and the transformation products are totally martensites when the cooling rate reaches 30 ℃/s. Ti micro-alloying deceases the Ms temperature, and the precipitation of Ti(C, N) phase refines the austenite grain size and therefore the lath martensites, which improves the strength of the tested steel by the effects of precipitation strengthening and fine grain strengthening.

Key words: cooling rate, titanium, hot press forming steel, CCT curve

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